A method for detecting a remaining toner amount in a developing device used in an image forming apparatus, such as an electrophotographic apparatus, may be a capacitance detection method that provides information relating to the remaining toner amount by detecting a capacitance between two electrodes provided in the developing device.
In particular, if a developing device including a development roller serving as a toner bearing member, and a supply roller having a foam layer serving as a toner supply member is used, the capacitance detection method may be a method that provides information relating to the remaining toner amount by detecting a capacitance between a shaft of the development roller and a shaft of the supply roller. The method is, for example, disclosed in Patent Literature 1. In this method, since the remaining toner amount of the developing device is correlated with the capacitance between the shafts, the remaining toner amount can be measured by detecting the capacitance.
When the image forming apparatus that measures the remaining toner amount by detecting the capacitance in the developing device is used, if temperature and humidity environment is changed, the capacitance may be changed. The measurement accuracy for the remaining toner amount may be degraded, and the image forming apparatus may not notify a user that the remaining toner amount is smaller than a predetermined amount or that a cartridge has to be replaced. To reduce the influence by the change in environment, for example, Patent Literature 2 discloses a technique that corrects timing of a notice by using a temperature sensor and a humidity sensor.